Method and apparatus for signaling in digital radio systems

ABSTRACT

A method and apparatus for transmitting data are provided. In the method, data streams are mapped onto frames, a word is generated including information for receiving the data streams for a given frame, and parity bits are derived from the word for the given frame. The data is arranged in the frames. Each of the frames includes a preamble and a data section. The preamble and the data section are time-multiplexed. The data section includes at least a part of the data streams, and the preamble includes signaling information. The word is inserted in a preamble section of the given frame, and one of the parity bits is inserted in a preamble section of a prior frame preceding the given frame. A part of the word for the given frame is inserted within a data section of an earlier frame preceding the prior frame. The frames are then transmitted.

PRIORITY

This patent application claims priority under 35 U.S.C. §119(a) toPatent Application Serial No. GB 1014432.7; which was filed in theUnited Kingdom Intellectual Property Office on Aug. 31, 2011, thecontent of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to wireless communicationsystems, and more specifically, but not exclusively, to a method andapparatus for signaling physical layer information in a broadcastsystem.

2. Description of the Related Art

A wireless communication system, such as a Digital Video Broadcasting(DVB) system, transmits data in a sequence of frames. For example, a DVBsystem may operate according to a DVB-Terrestrial 2^(nd) Generation (T2)standard, an Advanced Televisions Systems Committee (ATSC) standard, anIntegrated Services Digital Broadcasting (ISDB) standard, or a Digitalmultimedia Broadcasting (DMB) standard. Each frame typically includes apreamble section and a data section, which are time-multiplexed. Thedata section carries data arranged in a number of data streams, whichare commonly referred to as Physical Layer Pipes (PLPs). For example, aPLP may carry a service, such as a video channel provided to a user.

Reception of data from the frames, and reception of the data streams,may be assisted by signaling, which is typically carried in the preambleof the frame, i.e., Out-of-Band (OB) signaling, and/or carried in thedata section, typically of the preceding frame, i.e., In-Band (IB)signaling. The signaling may be referred to as physical layer signaling,or Layer 1 (L1) signaling. The signaling may indicate a modulation orcoding scheme to be used for decoding data, and sections of a data fieldto be decoded, or the location of a data stream within the data section.

The efficiency of L1 signaling, in particular, for battery-powereddigital broadcasting receivers in a mobile environment, may be measuredmainly from the perspectives of Robustness, Power Consumption, delay inchanging channels (“zapping” delay), and Latency. Prior art systems inthe mobile broadcasting context may suffer from insufficient robustnessof L1 signaling as compared to robustness of data. This is quitecritical as the L1 signaling is important to access the data later inthe frame. Accordingly, if the L1 signaling is lost, the data will belost too. The lack of robustness is mainly due to the lack of timediversity as the L1 signaling, in particular, OB signaling, may belocated at the beginning of a frame and typically does not apply anytime interleaving across the frame.

In order to alleviate this problem, some solutions have been proposedand adopted as options in the context of the DVB-T2 standard.Specifically, a repetition solution repeats the L1 signalingcorresponding to a next frame, in a current frame. Thus, the L1signaling has two copies, one in the previous frame and another one inthe current desired frame, which improves the robustness at the expenseof doubling the overhead, i.e., reducing the spectral efficiency.

Additionally, IB signaling has been proposed, which involvesencapsulating the L1 signaling for accessing and decoding data at afollowing frame into a data section of a current frame. In thisproposal, the signaling is time interleaved and benefits from a higherdiversity. However, the IB signaling is applicable for continuousreception only, but not for initial scanning, zapping, or updating. IBsignaling may provide some improved service continuity at goodrobustness, but still not enough, or in low mobility scenarios.

Specifically, conventional systems do not provide an efficient L1signaling solution that achieves robustness for initial scanning,service continuity, zapping, and updating, and is applicable in avariety of mobility scenarios.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made to solve theabove-described problems occurring in the prior art, and to provide atleast the advantages described below.

In accordance with an aspect of the present invention, a method isprovided for transmitting data including a plurality of data streams ina wireless communication system. The method includes mapping a pluralityof data streams onto a plurality of frames; generating a signalinginformation word including information for receiving the plurality ofdata streams for a given frame; deriving a plurality of parity bits fromthe signaling information word for the given frame; arranging the datain the plurality of frames, each of the plurality of frames including apreamble section and a data section, the preamble section and the datasection being time-multiplexed, the data section including at least apart of the plurality of data streams, and the preamble sectionincluding signaling information; inserting the signaling informationword in a preamble section of the given frame; inserting at least one ofthe plurality of parity bits in a preamble section of a prior framepreceding the given frame; inserting at least part of the signalinginformation word for the given frame within a data section of an earlierframe preceding the prior frame; and transmitting the plurality offrames.

In accordance with another aspect of the present invention, transmissiondevice is provided for transmitting data including a plurality of datastreams in a wireless communication system. The transmission deviceincludes a mapper for mapping a plurality of data streams onto aplurality of frames; a controller for generating a signaling informationword including information for receiving the plurality of data streamsfor a given frame, deriving a plurality of parity bits from thesignaling information word for the given frame, arranging the data inthe plurality of frames, each of the plurality of frames including apreamble section and a data section, the preamble section and the datasection being time-multiplexed, the data section including a part of theplurality of data streams, and the preamble section including signalinginformation, inserting the signaling information word in a preamblesection of the given frame, inserting at least one of the plurality ofparity bits in a preamble section of a prior frame preceding the givenframe, inserting part of the signaling information word for the givenframe within a data section of an earlier frame preceding the priorframe; and a transmitter for transmitting the plurality of frames.

In accordance with another aspect of the invention, a method is providedfor receiving data including a plurality of data streams in a wirelesscommunication system. The data is arranged in a plurality of frames,each frame including a preamble section and a data section. The preamblesection and the data section are time-multiplexed. The data sectioncarries at least parts of the plurality of data streams, and thepreamble section carries at least signaling information. The preamble ofa given frame has a signaling information word in a preamble section ofthe given frame. The signaling information word carries signaling forassisting in the reception of the plurality of data streams for thegiven frame. A preamble section of a prior frame preceding the givenframe has at least one of a plurality of parity bits derived from thesignaling information word for the given frame. The method includesreceiving a part of the signaling information word for the given framewithin the data section of an earlier frame, the earlier frame precedingthe prior frame; and determining whether or not to receive the signalinginformation word for the given frame included in the preamble of thegiven frame and the at least one parity bit included in the preamble ofthe prior frame, based on information derived from the earlier frame.

In accordance with another aspect of the present invention, a receivingdevice is provided for receiving data including a plurality of datastreams in a wireless communication system, the data being arranged in aplurality of frames, each of the plurality of frames including apreamble section and a data section, the preamble section and the datasection being time-multiplexed, the data section carrying parts of theplurality of data streams, and the preamble section carrying signalinginformation, the preamble of a given frame including a signalinginformation word in a preamble section of the given frame, the signalinginformation word carrying signaling for assisting in reception of theplurality of data streams for the given frame, and a preamble section ofa prior frame preceding the given frame including at least one of aplurality of parity bits derived from the signaling information word forthe given frame. The receiving device includes a receiver for receivinga part of the signaling information word for the given frame within thedata section of an earlier frame, the earlier frame preceding the priorframe; and a controller for determining whether or not to receive thesignaling information word for the given frame included in the preambleof the given frame and the at least one parity bit included in thepreamble of the prior frame, based on information derived from theearlier frame.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentinvention will be more apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates conventional signaling in a sequence of data frames;

FIG. 2 illustrates signaling in a sequence of data frames according toan embodiment of the invention;

FIG. 3 illustrates a data frame format according to an embodiment of theinvention;

FIG. 4 illustrates encapsulation of IB signaling according to anembodiment of the invention;

FIG. 5 illustrates a baseband header according to an embodiment of theinvention;

FIG. 6 illustrates IB signaling content according to an embodiment ofthe invention;

FIG. 7 illustrates L1-Pre OB signaling content according to anembodiment of the invention;

FIG. 8 illustrates L1-Config OB signaling content according to anembodiment of the invention;

FIGS. 9A and 9B are a flow charts illustrating a signaling method of areceiver according to an embodiment of the invention;

FIG. 10 is a graph illustrating frame error rates for various signalingtypes according to an embodiment of the invention;

FIG. 11 is block diagram illustrating a transmission device according toan embodiment of the invention; and

FIG. 12 is block diagram illustrating a receiving device according to anembodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Various embodiments of the present invention will be described in detailbelow with reference to the accompanying drawings In the followingdescription, detailed explanations of known related functions andconstitutions may be omitted to avoid unnecessarily obscuring thesubject manner of the present invention.

By way of example, embodiments of the present invention will bedescribed below with reference to a DVB Next Generation Handheld(DVB-NGH) standard, which is based on the 2^(nd) generation terrestrialDVB-T2 system. However, it will be understood that these embodiments arenot limited to the DVB-NGH) standard, and may involve other wirelesssystems. Additionally, the described embodiments are not limited totransmitting digital video signals.

In accordance with an embodiment of the present invention, a robust andefficient method is provided for signaling Layer 1 information. Themethod is applicable to different uses, such as an initial scan, zapping(channel switching), an update, and service continuity.

FIG. 1 illustrates conventional signaling in a sequence of data frames.Specifically, FIG. 1 illustrates conventional Layer 1 signaling.

Referring to FIG. 1, the sequence of data frames includes frames 2 a, 2b, 2 c, and 2 d. The preamble of each frame is represented by thesections indicated as L1-Pre and L1-Post. Typically, the L1-Pre sectionincludes signaling information relating to a modulation and codingscheme for receiving the L1-Post section of the preamble. The L1-Postsection includes information for receiving the data section, and inparticular, a data stream or PLP, within the data section. For example,the information includes a start address of a PLP within the datasection. The signaling information within the preamble may be referredto as OB signaling.

In FIG. 1, L1-Pre signaling information included in preamble 6 of frame2 a is used to receive L1-post signaling information, which is then usedto receive a PLP 10 within data section 8 of frame 2 a.

Signaling information is included within the data section 8 of frame 2a, typically, within a PLP. That is, the data section 8 of frame 2 aincludes IB signaling information, relating to the next data frame,i.e., frame 2 b. Data from frame 2 b, may then be decoded using the IBsignaling information. This type of signaling is advantageous in thatthe preamble of the next data-frame need not be received, saving powerconsumption at a receiver, and also allowing the signaling informationcarried in-band to benefit from the error correction coding of the datasection. A similar process is repeated in frame 2 c.

However, as illustrated in frame 2 d of FIG. 1, the reception of the IBsignaling may be corrupted by errors in the data section of the framethat may be caused by reception conditions being temporarily poor, e.g.,due to a weak signal or due to interference. In this case, in frame 2 d,the receiver switches to using OB signaling information from thepreamble.

However, the signaling of FIG. 1 suffers from the OB signaling lackingrobustness, such that when the receiver falls back to using OB signalingbecause of detection of errors in the data section of a frame, the OBsignaling may also be in error. Furthermore, the IB signaling is oflimited robustness, being typically no more robust than the datasection.

FIG. 2 illustrates signaling in a sequence of data frames according toan embodiment of the invention, which overcomes these problems in theconventional signaling.

Referring to FIG. 2, in frame 4 a, the L1-Pre signaling is used toreceive the L1-Post signaling as before, and this is used to receive thedata section of the frame. In this case, the L1-post signaling includesL1-dyn (dynamic) and L1-config (configuration) components. L1-dynrelates to a position of a PLP within the data section of a frame, andis typically transmitted in the preamble of each frame. L1-configrelates to a change in configuration of a frame and may beintermittently transmitted to indicate a change in the configuration.

In FIG. 2, at least one parity bit, which is derived from the signalinginformation in the preamble of a given frame, is included in thepreamble of a prior frame. In this example, the at least one parity bitis one of a plurality of parity bits derived from the L1-Post part ofthe signaling information. Specifically, a parity bit, i.e., anAdditional Parity (AP), is included in frame 4 a, which is used toreceive, using error correction, signaling information, in this caseL1-post, included in the preamble of frame 4 b, which may in turn beused to receive the data section of frame 4 b. An advantage of using theparity bit from a previous frame is that the coding of the signalinginformation gains from time diversity, in comparison with coding onlywithin the preamble of a given frame.

Referring to FIG. 2, IB signaling relating to a given frame, in thisexample, frame 4 c, is included within the data section of an earlierframe, i.e., frame 4 a, preceding the prior frame including the at leastone parity bit AP. Accordingly, if there is an error in the data sectionof frame 4 c, which includes signaling information relating to frame 4e, the receiver has sufficient warning that it may receive the prioritybits from the AP section of the following frame, i.e., frame 4 d, whichcan then be used with the OB signaling information in the preamble offrame 4 e to receive the data from frame 4 e.

Various embodiments of the invention may have the following features.

AP of the OB signaling may be placed in I_(AP) previous frames, in orderto improve robustness due to time diversity available across differentframes.

IB signaling may cooperate with the AP, thus pointing out I_(AP)+1 nextframes, compared to the 1 next frame in the conventional art. Thisallows the use of AP in case of failure or inability to use IBsignaling.

Further, a new field may be introduced in the IB signaling field forcooperation with the AP, which informs the receiver to startaccumulating the AP for decoding the OB signaling, e.g., wheninformation in the L1-Post, which is not included in the IB, changes.

Individual Cyclic Redundancy Check (CRC) may be introduced for the IBsignaling and data in the same PLP, instead of joint CRC as in theconventional art, thereby improving the error detection probability ofthe IB signaling.

IB signaling may be split into a fixed length part for use in PLPservice continuity and a variable part for use in signaling updates orannouncements only available in the OB signaling, such that the receiverdecodes the OB signaling as signaling in the IB signaling.

IB signaling and related CRC bits may be mapped to the Low DensityParity Check (LDPC) coded bits of high degree, i.e., high reliability,thereby improving the reliability of error detection decisions due tothe more robust CRC bits for the IB signaling.

As described above, the different embodiments of the present inventionintroduce different novel features for L1 signaling in digitalbroadcasting systems. Compared to conventional signaling, e.g., DVB-T2,embodiments of the present invention provide the following advantages.

Robustness may be improved for the same overhead because of the APspread across different frames (time diversity gain).

The power consumption may be preserved because of the AP being localizedin the frame (appended to the OB signaling in the current frame and notspread within the frame).

Further, power consumption may be reduced because of decoding the APonly on a need basis, i.e., after failure of IB signaling or anannouncement or update carried only in following OB signaling.

Higher error detection capability may be provided for the IB signalingbecause of individual CRC and more robust CRC bits, and signaling bitsmay be provided because of the mapping to high robustness LDPC bits.

Embodiments of the invention can provide a cooperative scheme between anenhanced IB signaling and an enhanced OB signaling (additional parity),thereby improving the service continuity and enable reliable receiverdecoding for updates or announcements during the service continuity. Aninitial scan and zapping, i.e., switching content channels, can stillwork with the solution of the present invention simply by resorting tothe OB signaling without the AP, in order to avoid zapping delay.

IB signaling may point to at least two (I_(AP)+1) frames ahead with APcontinuously inserted in at least one (I_(AP)) frame prior to the framecarrying the corresponding OB signaling (L1-Post-Dyn part).

When failing to successfully decode the IB signaling, the receiverstarts accumulating the AP to ensure successful decoding of the OBsignaling and avoid error propagation.

IB signaling may announce the existence and details of an AP inserted inthe super-frame preceding the one within which the receiver is requestedto switch over to the OB signaling (L1-Pre, L1-Post-Config) in order toacquire the L1/L2 update. That is, the IB signaling may inform thereceiver of the AP details to start accumulating in order to ensuresuccessful switch-over to the OB signaling to acquire the L1/L2 updatesby the transmitter.

IB signaling may have individual CRC to improve the reliability of errordetection with an optional mapping to the high degree bits of the LDPCFEC for more robustness.

The receiver may detect the IB signaling failure because the IBsignaling individual CRC, and upon detecting the failure (independentlyof the data success or not), the receiver starts accumulating AP for usein the detection of OB L1-DYN.

In the event of failure of IB signaling, AP may be used for more robustOB signaling (L1-Dyn) as a fallback solution. The transmitter signalsthe number of AP blocks I_(AP), the start of 1st AP block, and thelength of all AP blocks, in the L1-Pre and L1-Config, and continuouslyinserts the AP blocks in the frames between the frames carrying adjacentIB signaling.

The receiver accesses the new AP signaling fields in L1-Pre andL1-Config and detects if an IB failure occurs through the individual IBCRC. If IB failure occurs, the receiver starts accumulating the APblocks from the next frame until the frame preceding the point of switchover to the OB signaling.

In the event of a L1/L2 information update, AP may be used for morerobust OB signaling (L1-Pre, L1-Config, L1-Dyn) for successful updateacquisition. The transmitter may, in some frames (selected by thescheduler) in the super-frame preceding the super-frame where theIB-to-OB switch over is required by the transmitter, signal in the IBfields (and corresponding OB) the type (e.g., L1-pre, L1-config, andL1-dyn), and the corresponding number, start, and length, of AP blocks,and may insert the AP blocks in the frames designated by the scheduler.The receiver then accesses the AP signaling in the IB (or if IB fails inall selected frames, access the AP signaling in the OB in the currentsuper-frame). For each type of OB signaling, the receiver startsaccumulating the corresponding AP blocks from the 1st designated framein the current super-frame until the 1st frame in the super-frame (pointrequired by the transmitter for the switch over to the OB signaling).

As described above, aspects of the present invention introduce L1signaling solutions and associated framing concepts that rely oncooperation between OB L1 signaling and IB L1 signaling, both of whichimprove robustness and efficiency as compared to the conventional art.

Table 1 below summarizes examples of different operations addressed bythe present invention. In Table 1, four operations are identified,namely, initial scan, zapping (i.e., changing a content channel), updateor announcement, and service continuity. In Table 1, “Out-of-band L1”refers to L1 signaling as in the conventional art, “Out-of-band L1+”refers to OB signaling according to the present invention, and “In-bandL1+” refers to IB signaling according to the invention.

TABLE 1 Summary of use cases and solutions. Out-of-band Out-of-band L1L1+ In-band L1+ Use case (state of art) (invention) (invention) Initialscan X Zapping X X  Update or X* X* Announcement Service X* X*continuity *Cooperation enabled

Referring to Out-of-band L1+, a performance improvement is brought tothe OB L1 signaling by the introduction of AP bits across a number ofprevious frames. The number of AP bits, their contents, and the numberof transporting frames are important design characteristics. Due to theadditional parity bits, the effective coding rate R_(1,eff)(initial+additional parity) is lower than the initial effective codingrate R_(0,eff) (Initial parity only). Therefore, robustness improveswhen using the additional parity at the expense of spectral efficiencyreduction. However, splitting the AP bits across different previousframes may have an advantage of bringing time diversity, as opposed towhen locating the additional parity in the same current frame. Splittingthe AP bits across different previous frames may performed whilepreserving the advantage of localized L1 signaling in terms of powerconsumption.

Referring to In-band L1+, enhancements to the IB signaling L1 provideshigher error protection but also cooperation with the out-of-band L1+presented above.

As described above, FIG. 1 illustrates a conventional solution for aDVB-T2 system. In this solution, at the initial stage, the receiverdecodes the OB L1-post signaling in order to access the data PLP. Thedata PLP embeds the IB signaling to decode the data PLP at the followingframe. The merit of the IB signaling may be mainly from the robustnessperspective, where the signaling benefits from the same reliability asfor the data. Thus, when the IB signaling is successfully decoded, thereceiver knows the signaling to access the data PLP in the followingframing, and therefore, it may not have to decode the OB signaling(L1-Post). However, when the IB signaling is subject to decoding errorin the current frame and the data will also likely be lost, or there arechanges in the signaling that are only reflected or transmitted in theL1-post (e.g., update or announcement use case), the receiver thendecodes the OB signaling (L1-post). The latter may suffer from lack ofrobustness, and therefore, failure to successfully use the IB signalingin the previous frame will propagate the error to the current frame dueto the weak OB fall-back solution. A potential improvement for therobustness of the OB signaling is to lower the coding rate, thuslowering the spectral efficiency,) of the out-of-band signaling, whichmay be used occasionally for the recovery of an IB signaling failure.

According to an embodiment of the present invention, cooperation isprovided between OB signaling with improved robustness because AP andthe adapted IB signaling. For this combination to work properly, the IBsignaling provides information for accessing the data PLP, after anumber I_(AP) of frames following the immediately following frame. Anexample is illustrated in FIG. 2, where AP of the OB signaling (L1-post)is transmitted in I_(AP)=1 previous frame, such that the IB signalingprovides the access to the desired PLP, after I_(AP)+1=2 followingframes.

In FIG. 2, the L1-dyn part of the L1-Post signaling is first used toaccess the data PLP at the initial stage. This allows the decoding ofthe data and IB signaling at the first frame. The IB signaling signalsthe data PLP at the third frame. At the second frame, the L1-dynsignaling with its AP from the first frame will be used to access thedata and embedded IB signaling. When the IB signaling fails or cannot beused, the receiver may then be able to rely on the L1-dyn in the desiredframe and its corresponding AP in the previous frame to access the dataPLP and IB signaling in the desired frame.

For successful cooperation between enhanced IB and OB signaling,especially, for an update or announcement, in accordance with embodimentof the invention, a field is provided in the IB signaling that informsthe receiver to start accumulating the AP to help decoding the OBsignaling, the OB signaling including the signaling information relatedto the announcement.

In accordance with an embodiments of the present invention, a separateerror detection capability is provided to the IB signaling, instead ofjoint error detection at the frame level.

Specifically, for long frames at relevant operating Bit Error Rates(BERs), e.g., 10⁻⁴, an overall frame error is more likely than an IBsignaling error inside the frame, as the IB signaling has a shortlength. Therefore, declaring the IB signaling erroneous, as a result ofa frame error, may not be accurate for the IB signaling.

In accordance with an embodiment of the present invention, in order toprovide equal error detection, i.e., accurate for the overall frame andthe IB signaling, an individual CRC is included for the IB signaling.The IB signaling can also be decomposed into a fixed length part for PLPservice continuity, and a variable part for an announcement.

Further, the IB signaling and related CRC bits may be mapped to the LDPCcoded bits of high degree, i.e., high reliability, which may not impactthe LDPC decoding robustness, but provides better error correctionprobability of the IB signaling bits, which may ensure more reliableerror detection decisions based on more correct/reliable IB signalingCRC bits.

FIG. 3 illustrates a data frame format according to an embodiment of theinvention.

Referring to FIG. 3, the preamble section includes AP fields 12 a, 12 band 12 c. Additionally, L1-Conf and L1-Dyn may be encoded together togenerate the L1-Post. Further, an optional L1-Dyn Ext could betransmitted when the length of the L1-Dyn is not sufficient, whereL1-Dyn Ext is encoded separately. The length of the L1-Dyn Ext issignaled in the normal L1-Dyn. The number of Additional Parity blocks Nis equal to IAP and each parity block APi includes additional paritybits for the OB signaling transmitted i frames after the current frame.

FIG. 4 illustrates encapsulation of IB signaling according to anembodiment of the invention. Specifically, in FIG. 4 two options forencapsulating the BBFrames and the IBS are illustrated.

The first option, which corresponds to the SoA, illustrates IB signalingtransmitted after the payload. The use of IB is signaled in the OB, andthe length of the IB is obtained from the BBHeader.

In the second option, the IB signaling is placed just after theBBHeader, such that the IB bits are mapped to bits that are moreprotected by the LDPC.

Referring to FIG. 4, IB signaling 14 may optionally be placed towardsthe beginning of a data stream frame, i.e., a baseband frame 16.

FIG. 5 illustrates a baseband header according to an embodiment of theinvention.

Referring to FIG. 5, the position of signaling information within aphysical layer pipe is indicated by a header of a baseband frame.

Referring to FIG. 5, two options are illustrated for signaling the IBlength. In the first option, the SoA solution is modified replacing onebyte previously used to signal the Input Stream Identifier by the IBlength. In a second option, an extra byte is added to the BBHeaderincluding the length of the IB length.

FIGS. 6, 7, and 8 illustrate IB signaling content according to anembodiment of the invention.

Specifically, FIG. 6 illustrates IB signaling content according to anembodiment of the invention.

Referring to FIG. 6, a flag 18 is included to indicate an L1 change atthe next superframe. Also, signaling 20 is included to signal AP in theevent of L1 changes, and an individual CRC 22 is also signaled.

FIG. 7 illustrates L1-Pre OB signaling content according to anembodiment of the invention.

Referring to FIG. 7, a separate L1-config and L1-dyn parts have separatesignaling for each field identified as 24.

FIG. 8 illustrates L1-Config OB signaling content according to anembodiment of the invention.

Referring to FIG. 8, an IB pointer 26 and signaling of AP 28 are added.

FIGS. 9A and 9B are flow charts illustrating a signaling method of areceiver according to an embodiment of the invention.

Referring to FIG. 9A, in step S8.1 the receiver determines if L1-Pre andL1-Config are available for a j superframe. If the L1-Pre and theL1-Config are not available for the j superframe, in step S8.2 thereceiver waits for P1 and applies a frequency time synchronization. Instep S8.3, the receiver retrieves P2 symbols.

In step S8.4, the receiver determines if the L1-Pre is available for thej superframe. When the L1-Pre is not available for the j superframe, thereceiver decodes the L1-Pre in step S8.5.

In step S8.6, the receiver determines if the L1-Pre is decodedcorrectly. When the L1-Pre is decoded correctly, the L1-Pre is stored instep S8.7. However, when the L1-Pre is not decoded correctly in stepS8.6, the procedure returns to step S8.2, where the receiver again waitsfor P1 and applies a frequency time synchronization.

After storing the L1-Pre in step S8.7 or when the L1-Pre is availablefor the j superframe in step S8.4, the receiver determines if theL1-Config is available for the j superframe in step S8.8. When theL1-Config is not available for the j superframe, the receiver retrievesP2 symbols in step S8.9, and decodes L1-Config in step S8.10.

In step S8.11, the receiver determines if the L1-Config is decodedcorrectly. When L1-Config is decoded correctly, the L1-Config is storedin step S8.12. However, when the L1-Config is not decoded correctly instep S8.11, the procedure returns to step S8.2, where the receiver againwaits for P1 and applies a frequency time synchronization.

After storing the L1-Config in step S8.12 or when the L1-Pre and theL1-Config are available for the j superframe in step S8.1, the receiverdetermines if L1-Dyn(p) is available for an i+I_(AP) frame in stepS8.13, as illustrated in FIG. 9B.

When the L1-Dyn(p) is not available for the i+I_(AP) frame in stepS8.13, in step S8.14, the receiver retrieves P2 symbols and stores APfor L1-dyn signaling.

When the L1-Dyn(p) is available for the i+I_(AP) frame in step S8.13 orafter step S8.14, the receiver determines if a PLP_L1_Change_Flag isavailable for an i−1 frame in step S8.15. When the PLP_L1_Change_Flag isnot available for the i−1 frame, the receiver retrieves P2 symbols andstores AP for L1-pre and L1-config signaling in step S8.16.

When the PLP_L1_Change_Flag is not available for the i−1 frame in stepS8.15 or after step S8.16, the receiver determines if L1-Dyn isavailable for an i frame in step S8.17. When the L1-Dyn is not availablefor the i frame in step S8.17, the receiver decodes L1-Dyn in step S8.18and determines if L1-Dyn is decoded correctly in step S8.19. When theL1-Dyn is not decoded correctly, the procedure ends.

When the L1-Dyn is decoded correctly, the receiver decodes IB signalingfor a p-th PLP for an i+I_(AP)+1 frame in step S8.21, and determines ifthe IB signaling is decoded correctly in step S8.21. When the IBsignaling for the p-th PLP for the i+I_(AP)+1 frame is not decodedcorrectly, the procedure ends.

When the IB signaling for the p-th PLP for the i+I_(AP)+1 is decodedcorrectly, the receiver stores L1-Dyn(P) for the i+I_(AP)+1 frame instep S8.22.

FIG. 10 is a graph illustrating frame error rates for various signalingtypes according to an embodiment of the invention. Specifically, FIG. 10presents a Frame Error Rate (FER) measured as a function of the Signalto Noise Ratio (SNR) for different scenarios.

Referring to FIG. 10, a TU-6 channel model is assumed with 80 Hz Dopplerfrequency. The IB signaling MODulation and CODing (MODCOD) is QuadraturePhase Shift Keying (QPSK) with DVB-T2 16 k LDPC rate 4/9. The OBsignaling uses Binary Phase Shift Keying (BPSK) with DVB-T2 16 k LDPCrate 4/9, but an effective code rate ⅓. The OB signaling with AP alsouses BPSK and has effective code rate ⅓. Accordingly, the OB signalingwith or without AP has the same overhead.

A first scenario considers the IB signaling alone, i.e., without anycooperation with the OB signaling.

A second scenario considers the OB signaling alone, without AP.

The first and second scenarios represent reference scenarios in theconventional art, e.g., DVB-T2.

A third scenario shows the OB signaling alone, i.e., no cooperation withIB signaling, but with AP as proposed in the present invention.Comparing to the second scenario, the third scenario experiences a 1.5dB gain from the introduction of the AP to the OB signaling, i.e.,out-of-band L1+.

A fourth scenario shows a cooperative scheme of IB signaling and OBsignaling, without AP. The fourth scenario experiences significant gainbecause of the enabled cooperation of two nearly independent errorevents on the OB and IB signaling, compared to the first scenario andthe second scenario, supporting the merit of enabling the cooperation,even when not using the AP as proposed in this invention.

A fifth scenario shows the cooperative scheme of IB signaling and OBsignaling with AP, as proposed by the present invention. Compared to thecooperative fourth scenario without AP, the AP of the fifth scenariobrings a significant gain of nearly 0.8 dB.

Thus, as a first conclusion, a cooperative scheme between IB and OBsignaling provides a significant gain up to 1 dB, when compared to theconventional art, e.g., FIG. 1.

Further, enhancements of the IB signaling with individual CRC andmapping of IB signaling bits to high reliability LDPC bits provideshigher gain, because the cooperative scheme performs as the product ofOB and IB signaling, such that any improvement of the IB signaling mayconvert into performance improvement of the cooperative scheme. As aresult, the gain of a co-operative scheme may be higher than 0.8 dB.

FIG. 11 is block diagram illustrating a transmission device according toan embodiment of the invention.

Referring to FIG. 11, the transmission device includes a mapper 1101, acontroller 1102, and a transmitter 1103. The mapper 1101 maps aplurality of data streams onto a plurality of frames, under the controlof the controller 1102. For example, the controller 1102 controls themapper 1101 to map onto the frames in accordance with any of theabove-described methods. The transmitter 1103 transmits the framesincluding the plurality of data streams.

FIG. 12 is block diagram illustrating a receiving device according to anembodiment of the invention.

Referring to FIG. 12, the receiving device receives data including aplurality of data streams, the data being arranged in a plurality offrames, wherein each of the plurality of frames including a preamblesection and a data section. The receiving device includes a receiver1201 for plurality of frames, and a controller 1202 for processing thereceived plurality of frames in accordance with the above-describedmethods, e.g., in accordance with the method illustrated in FIGS. 9A and9B.

The above-described embodiments are to be understood as illustrativeexamples of the present invention. It is to be understood that anyfeature described in relation to any one embodiment may be used alone,or in combination with other features described, and may also be used incombination with one or more features of any other of the embodiments,or any combination of any other of the embodiments.

While the present invention has been shown and described with referenceto certain embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present invention asdefined by the appended claims and their equivalents.

What is claimed is:
 1. A method of transmitting data including aplurality of data streams by a transmitter in a wireless communicationsystem, the method comprising: mapping a plurality of data streams ontoa plurality of frames; generating a signaling information word includinginformation for receiving the plurality of data streams for a givenframe; deriving a plurality of parity bits from the signalinginformation word for the given frame; arranging the data in theplurality of frames, each of the plurality of frames including apreamble section and a data section, the preamble section and the datasection being time-multiplexed, the data section including parts of theplurality of data streams, and the preamble section including signalinginformation; inserting the signaling information word in a preamblesection of the given frame; inserting at least one of the plurality ofparity bits in a preamble section of a prior frame preceding the givenframe; inserting part of the signaling information word for the givenframe within a data section of an earlier frame preceding the priorframe; and transmitting the plurality of frames.
 2. The method of claim1, further comprising inserting another one of the plurality of paritybits in a preamble of a frame preceding the prior frame.
 3. The methodof claim 2, further comprising inserting part of the signalinginformation word for the given frame within the data section of theearlier frame preceding the prior frame.
 4. The method of claim 3,wherein the earlier frame precedes the frame preceding said prior frame.5. The method of claim 1, further comprising inserting a first indicatorwithin the data section of the earlier frame, the first indicatorindicating that a receiver should hold at least one of the plurality ofparity bits.
 6. The method of claim 1, wherein the data section of theearlier frame includes a start address of a first frame having apreamble that includes at least one of the plurality of parity bitsrelating to the given frame.
 7. The method of claim 1, wherein the datasection of the earlier frame includes a length of a block including theat least one of the plurality of parity bits relating to the givenframe.
 8. The method of claim 1, further comprising inserting a secondindicator within the data section of the earlier frame, the secondindicator indicating that the receiver should use signaling informationderived from preambles of at least one following frame to assistreception of the parts of the plurality of data streams carried by thedata section of the earlier frame.
 9. The method of claim 8, wherein thesecond indicator further indicates that the receiver should not usesignaling derived from the part of the signaling information word forthe given frame within the data section of the earlier frame.
 10. Themethod of claim 1, wherein the earlier frame is included in asuper-frame preceding a super-frame including the given frame.
 11. Themethod of claim 10, wherein the earlier frame is located in a later halfof the super-frame preceding the super-frame including the given frame.12. The method of claim 1, wherein the earlier frame is included in asame super-frame as the given frame.
 13. The method of claim 1, whereinthe signaling information word includes a layer 1 signaling word. 14.The method of claim 1, wherein the signaling information word includessignaling information related to one of the plurality of data streams.15. The method of claim 1, wherein the signaling information includes astart address of a first frame having a preamble that includes at leastone of the plurality of parity bits relating to the given frame.
 16. Themethod of claim 1, wherein at least one parity bit relating to signalinginformation related to one of the plurality of data streams is insertedinto each frame of a plurality of frames within a superframe.
 17. Themethod of claim 1, wherein the part of the signaling information word isincluded within one of the plurality of data streams.
 18. The method ofclaim 17, wherein a start address of the data stream frame is includedin a header of the one of the plurality of data streams.
 19. Atransmission device for transmitting data including a plurality of datastreams in a wireless communication system, the transmission devicecomprising: a mapper for mapping a plurality of data streams onto aplurality of frames; a controller for generating a signaling informationword including information for receiving the plurality of data streamsfor a given frame, deriving a plurality of parity bits from thesignaling information word for the given frame, arranging the data inthe plurality of frames, each of the plurality of frames including apreamble section and a data section, the preamble section and the datasection being time-multiplexed, the data section including a part of theplurality of data streams, and the preamble section including signalinginformation, inserting the signaling information word in a preamblesection of the given frame, inserting at least one of the plurality ofparity bits in a preamble section of a prior frame preceding the givenframe, inserting part of the signaling information word for the givenframe within a data section of an earlier frame preceding the priorframe; and a transmitter for transmitting the plurality of frames.
 20. Amethod of receiving data including a plurality of data streams by areceiver in a wireless communication system, the data being arranged ina plurality of frames, each of the plurality of frames including apreamble section and a data section, the preamble section and the datasection being time-multiplexed, the data section carrying parts of theplurality of data streams, and the preamble section carrying signalinginformation, the preamble of a given frame including a signalinginformation word in a preamble section of the given frame, the signalinginformation word carrying signaling for assisting in reception of theplurality of data streams for the given frame, and a preamble section ofa prior frame preceding the given frame including at least one of aplurality of parity bits derived from the signaling information word forthe given frame, the method comprising: receiving a part of thesignaling information word for the given frame within the data sectionof an earlier frame, the earlier frame preceding the prior frame; anddetermining whether or not to receive the signaling information word forthe given frame included in the preamble of the given frame and the atleast one parity bit included in the preamble of the prior frame, basedon information derived from the earlier frame.
 21. The method of claim20, wherein the information derived from the earlier frame is derivedfrom a first indicator within the data section of the earlier frameindicating that the receiver should use a signaling information wordderived from the preamble of at least one following frame to assistreception of the parts of the plurality of data streams carried by thedata section of the given frame.
 22. The method of claim 21, furthercomprising: detecting a second indicator within the data section of theearlier frame, the second indicator indicating that the receiver shouldhold at least one of the plurality of parity bits, the at least one ofthe plurality of parity bits being received from a preamble of a framefollowing the earlier frame and preceding the given frame; holding theat least one of the plurality of parity bits; processing the signalinginformation word using the at least one of the plurality of parity bits;and assisting the reception of data from the given frame relating to atleast one of the data streams, using the signaling information word. 23.The method of claim 20, wherein the earlier frame is included in asuper-frame preceding a super-frame including the given frame.
 24. Themethod of claim 20, further comprising: detecting an error relating tothe data section of the earlier frame; and deriving the information fromthe earlier frame from the detection of the error.
 25. The method ofclaim 20, further comprising receiving the signaling information wordwithout using the plurality of parity bits.
 26. A receiving device forreceiving data including a plurality of data streams in a wirelesscommunication system, the data being arranged in a plurality of frames,each of the plurality of frames including a preamble section and a datasection, the preamble section and the data section beingtime-multiplexed, the data section carrying parts of the plurality ofdata streams, and the preamble section carrying signaling information,the preamble of a given frame including a signaling information word ina preamble section of the given frame, the signaling information wordcarrying signaling for assisting in reception of the plurality of datastreams for the given frame, and a preamble section of a prior framepreceding the given frame including at least one of a plurality ofparity bits derived from the signaling information word for the givenframe, the receiving device comprising: a receiver for receiving a partof the signaling information word for the given frame within the datasection of an earlier frame, the earlier frame preceding the priorframe; and a controller for determining whether or not to receive thesignaling information word for the given frame included in the preambleof the given frame and the at least one parity bit included in thepreamble of the prior frame, based on information derived from theearlier frame.